1. Field of the Invention
The present invention relates generally to vehicle lights, and more particularly it relates to vehicle light assemblies that incorporate a diffuser surface structure on a surface of the assembly which homogenizes, shapes and directs light exiting the light assembly.
2. Description of the Related Art
It is well known that automobiles use many different interior and exterior lights and light assemblies for various purposes on the vehicle. Other vehicles such as trucks, boats, motorcycles, bicycles, load carriers, airplanes, construction equipment and essentially any other type of vehicle also utilize many different lights and light assemblies. Most light assemblies utilized on vehicles are crude from an optics standpoint and employ rudimentary designs and constructions for convenience and appearance purposes. These types of lights include vanity mirror lights, license plate lights, dome lights, map reading lights, flood lights, instrument panel lights, displays and instrumentation, as well as other types of convenience illumination systems for vehicles. In contrast, certain vehicle light assemblies including headlamps, turn signals, reflectors, brake lights and taillights are provided for safety purposes as well as for appearance. These more important types of lights employ slightly better technology in material and design but also employ only surprisingly crude optics in their design or construction primarily for aesthetic purposes. Very little thought is given to putting the light emanating from such light assemblies where it is most needed as to maximizing transmission efficiency of the assembly.
For example, the most important light utilized on nearly all vehicles is the headlight or forward illumination light so the operator can see ahead of the vehicle and so that others can see the vehicle as well. The taillights of vehicles are also important to make the rear of the vehicle visible in the dark to operators of other vehicles. Most of these types of lights employ a parabolic reflector surface disposed behind and partially surrounding a light source such as lamps or bulbs having a filament and LED""s. FIG. 1 illustrates a schematic of a typical light assembly such as a headlamp or a portion of a taillamp. The assembly 20 has a parabolic reflective surface 22 and a light source 24 spaced from the surface 22. The lines xe2x80x9cLxe2x80x9d indicate the directionality of light emanating from the source 24 and the path of light reflected by the reflector surface 20. As illustrated, the light generally passes from the source toward a transparent cover 26 or is reflected by the reflector forward toward the cover in a generally predetermined direction. However, in reality this type of light source has two significant problems which are typically not adequately addressed.
First, the light source 24 has a filament (not shown) that typically does not distribute light evenly. For example, incandescent or halogen bulbs are typically utilized for interior and exterior vehicle lighting systems. Each of these types of bulbs includes a filament housed within an enclosed chamber of the bulb. This chamber is somewhat pressurized where the amount of pressure depends on the type bulb utilized. Halogen bulbs are at a much higher pressure than a standard incandescent bulb. Failure of the bulb usually results from failure of the filament. The filament reacts with gases in the chamber or simply glows by application of energy to the filament to illuminate the bulb. These filaments do not evenly produce light and generate what are known as high intensity regions where more light is directed and low intensity regions where less light is directed. When utilizing a reflection type lighting system, the high and low intensity regions are simply reflected back out from the reflection and remain in the projected light from the assembly. These high intensity and low intensity regions make it difficult for an operator to see objects that the light is intended to illuminate. Such objects may be a map inside a car or may be more importantly a road surface or cars ahead of the vehicle making lane changes or braking. If the light assembly is not a reflection type but merely the type where a bulb or LED directs light from a housing through a lens or cover that spreads the, light the high intensity and low intensity regions are again merely projected as is from the lens.
Secondly, a lot of the light energy or photons are wasted in all different types of automotive or vehicle light assemblies. This is based upon the fact that much of the light leaving a bulb or other light source within the assembly is directed immediately outward from the light source and not directed toward a particular target by either the parabolic reflector surface or by the light source or the lens itself. Any light escaping the light assembly that is not directed toward a particular target is simply wasted. In automotive lighting systems, much of the light from any source is propagated away from the intended direction and wasted. This wasted and misdirected light can cause difficulty in the form of glare for individuals in the general area of the particular vehicle and the light source. xe2x80x9cMaskingxe2x80x9d of a light is sometimes resorted to in order to keep light from emanating in particular directions where it is not desired such as lane changes, lane illumination or braking. This further wastes light energy and adds further complexity to light assemblies.
Lens covers 26 are sometimes utilized in vehicle light assemblies which have certain lens design or shape characteristics formed therein. These lens characteristics are typically in the form of Fresnel optics, elongate cylindrical lenses, and pillow optics. Each of these types of lenses is intended to spread or otherwise disperse light exiting a light assembly. For example, FIGS. 2 and 3 illustrate very simple schematics of a light assembly utilizing cylindrical dispersion elements 30 (FIG. 2) and Fresnel optics 32 (FIG. 3). These are commonly utilized for vehicle taillamp constructions wherein a bulb 34 is held in a fairly deep and narrow housing 36 illuminating outward through an opening 38. Most taillight assemblies have a number of separate compartments, each one having its own light source and separate or at least distinct cover or lens design. A lens cover or cover section 40 is dispersed over the opening 38 in the housing 36. A Fresnel structure 32 or cylindrical dispersion element structure 30 is incorporated in the lens cover 40 to provide some spread of the light as it exits the housing. Other surface structures such as a prismatic or pillow optic structure are also commonly used. Each of these particular designs is fairly inefficient and does nothing to solve either of the above described problems. In fact, many vehicle light assembly designs are such that, though a lot of light would be lost without such a lens cover, more light may be wasted by utilizing the Fresnel optics or the cylindrical lens construction. This is because the light exiting the housing is further spread by the lens designs. Even more light is wasted where the lens cover is designed to mask light to prevent it from emanating in an undesired direction.
These same problems exist and in fact are enhanced by the more rudimentary designs of the bulbs, housings, reflector surfaces (if present) and lens cover designs for other types of less important vehicle lights such as interior dome lights, map lights, general illumination lights, dash lights, exterior hood and trunk lights, and other vehicle marker lights. Much light is spread to areas beyond a target thus wasting a lot of the light. Additionally, high and low intensity regions are also present for these much simpler designs. The severity of the high and low intensity regions depends upon the type of lens cover placed over the light.
Another element mentioned above and used in the art of vehicle light assembly design is known as xe2x80x9cpillow optics,xe2x80x9d such as are illustrated in FIGS. 4A, 4B and 4C. Pillow optics are relatively large structures 42a, 42b and 42c formed on one surface of a lens cover for a vehicle light assembly 46. The pillow optics 42a-c very inefficiently diffuse light exiting the light source 48 but more importantly are designed merely to enhance the light assembly""s and light""s aesthetic appearance. The shape, spacing, orientation, size and construction of the pillow optics for a particular light assembly such as for a vehicle taillamp or dome light or map light lend a particular desired appearance to the light assembly. However, the pillow optics provide very little or no real optical characteristics for these light assemblies and usually create further light dispersion and waste which is unnecessary, unwanted and even unsafe for certain types of vehicle light assemblies.
The assignee of the present invention has previously invented highly efficient light diffusing surfaces in the form of a light shaping surface microstructure and methods of forming these surfaces. The novel diffusers produce significantly enhanced homogenization of light dispersed from such a diffusing surface and are capable of directing light with a particular spread, shape, and angle of orientation or directionality. These methods and surface microstructure are described in a number of existing patents and co-pending applications, each commonly assigned to the assignee of the present invention. Each of the below listed patents and applications is incorporated herein by reference for its teachings as to the formation and construction of the diffuser surfaces.
Many of these methods involve creating a master diffuser by exposing a photoresist material to a source of light and then replicating this master diffuser into one or more submasters of a more durable nature. There are also other methods of making replicas of a master diffuser which contain the optical features in the master. With some of these methods, the master diffuser is initially created optically. With others, it is created mechanically. Submasters are created from these master diffusers utilizing a number of methods whereby the master diffuser surface is replicated into a submaster surface. These other methods are described in one or more of the below listed co-pending U.S. applications.
Commonly assigned U.S. patents and pending applications disclose related methods for making and recording optical products and replicating those products so that they may be mass produced. For example, U.S. Pat. No. 5,365,354 entitled xe2x80x9cGrin Type Diffuser Based on Volume Holographic Material,xe2x80x9d U.S. Pat. No. 5,534,386 entitled xe2x80x9cHomogenizer Formed Using Coherent Light and a Holographic Diffuser,xe2x80x9d and U.S. Pat. No. 5,609,939 entitled xe2x80x9cViewing Screen Formed Using Coherent Light,xe2x80x9d all owned by the present assignee relate to methods for recording and replicating optical products. Each of these U.S. patents is incorporated herein by reference for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
Related U.S. patent applications include U.S. Pat. No. 6,072,511, issued Jun. 6, 2000, entitled xe2x80x9cApparatus for LCD Backlighting,xe2x80x9d U.S. Pat. No. 6,159,398, issued Dec. 12, 2000, entitled xe2x80x9cMethod of Making Replicas While Preserving Master,xe2x80x9d U.S. Pat. No. 5,956,106, issued Sep. 21, 1999, entitled xe2x80x9cLCD With Light Source Destructuring and Shaping Device,xe2x80x9d U.S. Pat. No. 5,858,403, issued Nov. 17, 1998, entitled xe2x80x9cLiquid Crystal Display System with Collimated Backlighting and Non-Lambertian Diffusing,xe2x80x9d U.S. Pat. No. 5,735,988, issued Apr. 7, 1998, entitled xe2x80x9cMethod of Making Liquid Crystal Display System,xe2x80x9d U.S. Pat. No. 5,922,238, issued Jul. 13, 1999, entitled xe2x80x9cMethod of Making Replicas and Compositions for Use Therewith,xe2x80x9d U.S. Ser. No. 09/137,397, filed Aug. 20, 1998, entitled xe2x80x9cMethod and Apparatus for Making Optical Masters Using Incoherent Light,xe2x80x9d pending, U.S. Ser. No. 09/136,995, filed Aug. 20, 1998, entitled xe2x80x9cNon-Lambertian Glass Diffuser and Method of Making,xe2x80x9d pending, U.S. Ser. No. 09/137,398, filed Aug. 20, 1998, entitled xe2x80x9cDiffuser Master and Method of Manufacture,xe2x80x9d pending, U.S. Pat. No. 6,158,245, issued Dec. 12, 2000, entitled xe2x80x9cHigh Efficiency Monolithic Glass Light Shaping Diffuser and Method of Making, xe2x80x9d U.S. Ser. No. 09/139,488, filed Aug. 25, 1998, entitled xe2x80x9cOptical Element Having an Integral Surface Diffuser,xe2x80x9d pending, U.S. Pat. No. 6,166,389, issued Dec. 26, 2000, entitled xe2x80x9cApparatus Having a Light Source and a Sol-Gel Monolithic Diffuser,xe2x80x9d U.S. Ser. No. 09/139,455, filed Aug. 25, 1998, entitled xe2x80x9cPassive Matrix Liquid Crystal Display,xe2x80x9d pending, and U.S. Ser. No. 09/139,444, filed Aug. 25, 1998, entitled xe2x80x9cDevice Including an Optical Element With a Diffuser,xe2x80x9d pending. All the above applications are owned by the present assignee and are hereby incorporated by reference for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
The present invention is directed to vehicle lights and light assemblies which incorporate an optically improved diffuser micro-sculpted surface structure or microstructure into a surface of a lens or cover of the light assembly.
It is an object of the present invention to provide a vehicle light assembly which has greatly improved optical quality. It is another object of the present invention to provide a vehicle light assembly which has light homogenizing, directing, and shaping capabilities. It is a further object of the present invention to provide a vehicle light assembly which has dramatically improved homogenized light output from the light assembly. It is a further object of the present invention to provide a vehicle light assembly which is capable of directing light only to where it is needed and preventing light from being directed to where it will be wasted. It is a further object of the present invention to provide a vehicle light assembly which will produce less heat. It is another object of the present invention to provide a vehicle light assembly having an output shape distribution corresponding to the area to be illuminated. It is a further object of the present invention to provide a vehicle light assembly which improves many safety characteristics for vehicle lights such as automobiles, trucks and the like.
To accomplish these and other objects of the present invention, in one embodiment a vehicle light assembly has a light source and an at least partially transparent cover disposed over a portion of the light source. The cover has an inner surface adjacent to the light source and another surface facing away from the light source. A light shaping surface microstructure is integrally formed on a surface of the cover. The microstructure provide both a homogenized light output as well as light directing and shaping properties for directing light passing through the cover in a predetermined direction and distribution.
In one embodiment, the cover is molded from a plastic material and the microstructure is integrally molded on one of the surfaces of the cover. In one embodiment the microstructure is molded into the inner surface of the cover.
In one embodiment, the microstructure is combined with a plurality of relatively large pillow optic formations provided on a surface of the cover. The pillow optic formations are of any shape or construction but are provided primarily for aesthetic appearance characteristics. In one embodiment, the microstructure is incorporated directly into the surfaces of the pillow optics. In another embodiment, the microstructure is integrally molded on the surface of the cover opposite the pillow optic formations. Thus, the pillow optic formations and/or the microstructure may be provided on either the inner surface or the outer surface of the cover.
Such a construction can be utilized for virtually any type of vehicle light assembly including headlamps, taillamps, interior dome and map reading lights, interior instrument panel lights, exterior storage compartment lights for the hood or the trunk and for interior storage compartment lights.
In one embodiment, the vehicle light assembly includes a layered covered construction having an exterior cover section covering generally the entire light assembly and an interior layer or cover section having two or more discrete sub-sections, one each covering a separate light source held in compartments within the light assembly. Such a construction is typically utilized for vehicle taillight assemblies wherein the assembly includes several different types of lamps or light sources for different purposes, each held in a separate compartment and covered by a different discrete cover sub-section. In such an embodiment, the microstructure can be included on one or more of the sub-sections of the interior cover layer or on either side or any part or all of the exterior cover layer. The microstructure can therefor homogenize, direct and shape light provided from the appropriate light source, or from a combination of the light sources of the assembly. In any of these embodiments, the microstructure is integrally formed into the surface of the covered material during formation of the cover.
In one embodiment, the vehicle light assembly is a reflector wherein the light source is simply ambient light or light provided from another vehicle""s lights. In this particular embodiment a reflective surface may be applied to or placed adjacent a lens cover assembly. Alternatively, the reflection capabilities are provided within the reflector lens itself. The microstructure providing the homogenizing, directing and shaping capabilities can be provided on a surface of the reflector lens and integrally molded therein or may be provided on the separate reflective surface placed behind the reflector lens material.
In one embodiment, the vehicle light assembly includes a light source with a parabolic reflective surface disposed behind the light source for reflecting light emanating form the source outward through an opening of a housing of the assembly. In this embodiment, the microstructure providing the homogenizing, directing and shaping properties is provided directly on the parabolic reflective surface of the light assembly. Light emanating from the source reflects from the reflective surface having the appropriate properties provided by the microstructure.
In one embodiment, the light assembly is a high temperature and high strength headlamp assembly wherein the microstructure is integrally formed in a glass or sol-gel glass cover which is disposed over a light source. Such a light source can be a common halogen headlamp or bulb which generates excessive heat and requires a high temperature resistant material placed adjacent the bulb or any other light source. In such a headlamp construction, the microstructure may be recorded or molded directly into the sol-gel or glass material on either an inner surface or an outer surface or may be integrally formed into a separate second cover layer disposed over the enclosed glass headlamp construction. Alternatively the microstructure may be integral on the parabolic reflective surface of the assembly behind the light source.
In other embodiments, the microstructure may be integrally formed in a surface of a plastic cover such as a dome light or map light cover. The cover is then placed over a simple incandescent bulb light source. The cover may include pillow optic functions or simply be a smooth translucent plastic cover.
In any of these embodiments, the particular size, orientation and shape of the microstructure is designed and selected according to the functional characteristics of a particular vehicle and particular light assembly and function. For example, the microstructure may be designed to homogenize light emanating from a vehicle taillamp assembly as well as control the direction of the light within a particular envelope pattern having a specific vertical and horizontal spread. Critically by employing the microstructure into such a light assembly, virtually all of the light photons emanating from the light source are directed to where they are needed and not wasted in a vertical or horizontal direction as is common with presently known vehicle light assembly designs. The diffuser microstructure can be utilized to shape and homogenize light emanating from virtually any vehicle light assembly whether it be an exterior or interior light and can be designed to homogenize and direct the light as needed for each particular light.
These and other aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof and the invention includes all such modifications.